The present invention relates to an improvement in variable pitch propellers, through which it will be possible to replace a propeller blade under water without water intruding into the mechanism in the propeller hub and without a substantial quantity of oil leaking to the surrounding water.
A variable pitch propeller comprises a propeller hub and a number of propeller blades which may be turned and which are each removably attached to a crank disk which, in turn, is connected to an adjusting mechanism. The interior of the hub is filled with oil, and a seal is provided between the hub and the blade root of each propeller blade to prevent water from entering the hub and from damaging the adjusting mechanism. Further, the seal should prevent oil, present between the blade root and the adjacent "seating" in the hub to provide for lubrication, from leaking out to the surroundings.
Means have been suggested previously whereby a disk is located between the blade root and the seal which disk remains in its place and retains the sealing function when the blade is removed. This disk does, however, occupy space which could otherwise be utilized to provide optimal mechanical strength in hub and propeller blades. This sealing disk does consequently either involve a weakening of the structure or an undesired increase of the hub diameter along with substantial excess costs.